Test-retest reliability of a simplified questionnaire for screening adolescents with risk behaviors for eating disorders in epidemiologic studies

Abstract

Introduction: The number of people presenting abnormal eating behaviors based on the habit of going on strict diets and taking measures to compensate food consumption (use of laxatives, diuretics, and self-induced vomiting) is growing. There is a clear need for simple investigative tools in population-based studies. Objective: Evaluate the reliability of a simplified questionnaire to investigate risk behaviors for eating disorders (ED) among adolescents. Methods: The questionnaire had two questions: the second question was subdivided into four other ones, about the frequency of binge eating episodes, the use of laxatives and diuretics, self-induced vomiting, and strict dieting. It was applied in two moments (test-retest), with an interval of 15 days between the two assessments, in 195 students (70% girls) aged from 12 to 19.9 years, from a Niterói/RJ public school. The reliability of the questions was assessed through the weighted Kappa coefficient and their 95% respective confidence intervals (CI) and frequency adjusted kappa. Results: Frequency-adjusted kappa values for less frequent behaviors were: 0.93 for the use of laxatives, 0.97 for the use of diuretics and 0.92 for self-induced vomiting. For the more frequent risk behaviors for ED such as binge eating episodes and restrictive dieting, weighted Kappa coefficients were 0.50 and 0.61, respectively. Conclusions: The reliability of the questionnaire was good, with better results for investigating less frequent behaviors.